Timmerman 2004.

Study characteristics
Methods	Trial design: RCT – split‐mouth design Location: Centre for Dentistry, Amsterdam, the Netherlands Setting: closed operatory room Language: English Number of centres: 1 Study period: not mentioned Funding source: not mentioned Study protocol: not available
Participants	Age: 43 to 69 years Total number of participants: 6 (3 male, 3 female) Inclusion criteria: patients who were referred to the Academic Centre for Dentistry in Amsterdam (ACTA) for diagnosis and treatment of periodontitis patients who had at least 3 teeth in each quadrant patients who were diagnosed as having generalized chronic periodontitis Exclusion criteria: use of antibiotics or topical antiseptics during a period of 30 days prior to the study Number randomized: 6 Number evaluated (withdrawals/missing participants): 6
Interventions	Comparison: HVE versus conventional dental suction (low‐volume evacuator) Intervention: Group name: with HVE (high‐volume evacuation) Number of intervention groups: 1 Number randomized to intervention group: 6 Description of intervention: the study included 17 treatment sessions, consisting of a 40‐minute episode of continuous plaque and calculus removal using an ultrasonic unit (EMS). The treatment sessions were carried out in 6 patients with generalized adult periodontitis and ranged from 2 to 4 sessions per patient according to their needs. The use of HVE and CDS was randomly assigned over the sessions within each patient. Before each treatment, the operating room was not used for 15 hours. To measure baseline microbial air pollution 2 Petri dishes containing blood agar were exposed for 10 minutes to the air. At the start of each treatment session, 2 Petri dishes were exposed for 5 minutes at a distance of 40 cm from the mouth of the patients. After 20 minutes, this procedure was repeated. At a distance of 150 cm, 2 Petri dishes were exposed for 20 minutes followed by exposure of 2 new Petri dishes for the rest of the session. The plates were cultured aerobically and anaerobically for 3 and 7 days, respectively Any co‐interventions: no Comparator: Group name: with conventional dental suction (CDS) Number of control groups: 1 Number randomized to control group: 6 Description of control: as described above
Outcomes	Outcome name: reduction in contamination of aerosols Outcome measurement: CFU (using blood agar plates), both aerobic and anerobic culture were done Effect estimate: mean (SD) Key conclusions: the results of the present study showed no differences when different methods of suction were used. This might indicate that the amount of aerosol with small particle size, able to carry bacteria over a larger distance, as produced by the present piezoelectric device, is relatively limited. The use of a high‐volume evacuator may, however, help to minimize risks of air microbial contamination.
Notes	We contacted the study author for method of randomisation, allocation concealment, personnel blinding and study protocol. We sent an e‐mail on 26 July 2020 to the contact author and the e‐mail bounced back. We could not contact other authors as their e‐mail details are not available.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No details available
Allocation concealment (selection bias)	Unclear risk	No details available
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding is not possible. However, participants and personnel will not be able to alter their behaviour even if they know the received intervention.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	It is not clear if the CFU were manually counted or any automated colony counters were used – there is subjectivity if manually counted.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcomes of all 6 participants are reported
Selective reporting (reporting bias)	Unclear risk	We are not sure of reporting selective outcomes as there is no protocol available
Other bias	Low risk	None